The igloo is a dwelling that is associated with Eskimos and other northern peoples. It is build out of ice and snow, and uses the insulating properties of those materials to allow the interior to be heated to comfortable levels without melting. You can make a mini model of an igloo out of ice cubes, using salt to fuse the layers together. This project can be fun for school or science fairs.
Make several ice cubes in a tray. The best tray is one with little slope: you want the cubes to be as rectangular as possible.
Sprinkle salt on a cookie sheet and make a ring of 12 ice cubes.
Place the tray in the freezer until the bottoms of the ice cubes, which have been slightly melted by the salt, have refrozen.
Dip the bottoms of more ice cubes in salt and make a second ring on top of the first. Stagger these cubes as you would bricks, and space them 1/4 of the way inside of the first ring to begin sloping the sides.
Place the tray in the freezer to refreeze the salted portion of the ice, bonding the second ring to the first.
Make more ice cubes, this time only filling the tray halfway with water.
Make two to three rings with the half-size cubes, dipping each in salt and refreezing each ring. The rings should continue to get smaller, creating a dome shape.
Make additional ice cubes filling the tray 1/4 full. Use these ice cubes for the upper layers of the igloo.
Continue adding rings, each slightly smaller than the last, until the top of the igloo closes.
Make a doorway by lining up two lines of 2 to 3 ice cubes extending from the side of the igloo. Freeze and build up curving sides to the doorway the same way that you did with the main igloo body.
Blend leftover ice cubes to create a ice slush.
Coat the igloo in this fine ice slush to fill in the gaps between rings and smooth the outer surface. Refreeze it a final time.
In the winter months you can use actual snow for the final step, just like a real igloo.